He added that it was a “deliberate attempt to influence the outcome of elections” to be held in the province in three weeks.

Mr McConville, now 51, claims he recognised local faces when the gang arrived to drag his screaming mother away.

He said he had seen the people involved on the streets “on many occasions”, adding: “When I see them my blood boils.

“I just can’t stand these people for what they have done to us.

“We’re just happy to see everything moving as it is moving at the minute.

“Me and the rest of my brothers and sisters are just glad to see the police doing their job.

“We didn’t think it would ever take place (Adams’ arrest) but we are glad it has.

“All we’re looking for is justice for our mother. On the seventh of next month she would have been 80.

“If the IRA hadn’t have killed her, God knows, she still might still be alive today.

“Not a day goes by when I haven’t thought about my mother getting torn away.

“It’s like it was yesterday. I’ll never forget it and it won’t go away.”

Disappeared: Jean McConville, who was murdered by the IRA

The 37-year-old widow was dragged from her home in the Divis Flats by an IRA gang of up to 12 men and women.

There had been speculation she had helped an injured British soldier.

Others claimed she was an informer but this was dismissed after an official investigation.

When one of her children, 16-year-old Archie, had the courage to ask: “Can I go with yous and my mummy?” he was taken outside by a gunman who put a pistol to his head and told him: “F*** off.”

Today PM David Cameron’s official spokesman was asked if the arrest was politically motivated.

He said: “This is entirely and rightly so an independent police matter. There has been an ongoing investigation for a period of time now, as is well known.”

He added: “I would distinguish between what is a matter for the police in terms of the investigation into what was an appalling crime and separately the work that the British and Irish governments do in support of the Northern Ireland Assembly and work in Northern Ireland.”

But Sinn Fein deputy leader Mary Lou McDonald insisted the arrest was politically motivated and designed to damage the party and its president. Mr Adams, 65, has always rejected allegations by former republican colleagues that he had a role in the death.

No one has ever been charged but after years without progress there have recently been a series of arrests.

Veteran republican Ivor Bell, 77, was charged in March with aiding and abetting the murder. Five other people have been detained and questioned.

Niall Carson/PA Wire

Suspect: Gerry Adams

Mr Adams, who was detained after voluntarily presenting himself for interview, has always denied IRA membership.

In March he announced he would be available if detectives wished to speak to him. The former Belfast West MP, who stepped down in 2011 when he was elected to the Irish Parliament in Dublin, described the allegations as “malicious” and added: “While I have concerns about the timing, I am voluntarily meeting with the police.

“As a republican leader I have never shirked my responsibility to build the peace.”

Protestant-born Mrs McConville, who converted after marrying a Roman Catholic, was shot in the back of the head and buried on Shelling Hill Beach, Co Louth.

An investigation by the Northern Ireland Police Ombudsman rejected claims she was an informer.

Clearly embarrassed by the killing, the IRA did not officially admit responsibility until 1999 when information was passed to police in the Irish Republic. It was not until August 2003 that her remains were found by a man walking his dog.

In 1999 the Independent Commission for the Location of Victims’ Remains was established by a treaty between the British and Irish governments. It lists 16 people as “Disappeared”.

Timeline of the Republicans' man of war and peace

Gerry Adams was at the heart of the the IRA terror war from the 1960s but became a key part of the peace process who was lauded by men such as Nelson Mandela and Bill Clinton.

1960s - Adams first became involved in the nationalist campaign.

1972 - Interned without trial before being released in July to take part in secret talks in London.

1981 - After the H-Block hunger strikes, where 10 men starved themselves to death, he backed the policy of the “ballot box and the Armalite” and was elected as an MP in 1983.

1984 - He was shot and seriously wounded by a “unionist death squad working in collusion with British Intelligence”, according to Sinn Fein.

1988 - Among senior Republicans banned from Britain’s airwaves.

1994 - Prime figure in the IRA ceasefire after the historic Downing Street declaration a year earlier.

2007 - Joined historic power-sharing Government in Stormont with his old arch-enemy the Rev Ian Paisley.

2011 - Resigned his seat at Westminster and elected to the Irish Parliament, the Dáil.